High-Definition Videobronchoscopy for the Diagnosis of Airway Involvement in Sarcoidosis

Background The ability of high-definition (HD) videobronchoscopy to detect airway involvement in sarcoidosis has not been evaluated previously. Research Question What is the role of HD videobronchoscopy in the identification of sarcoidosis-associated airway abnormalities (AAs)? What are the patterns of AAs more commonly observed and more frequently associated with the detection of granulomas in endobronchial biopsy (EBB)? Study Design and Methods In this prospective international multicenter cohort study, consecutive patients with suspected sarcoidosis underwent airway inspection with an HD videobronchoscope and EBB using a standardized workflow. AAs were classified according to six patterns defined a priori: nodularity, cobblestoning, thickening, plaque, increased vascularity, and miscellaneous. We assessed diagnostic yield of EBB, prevalence of AAs, and interobserver agreement for different patterns of AAs. Results AAs were identified in 64 of 134 patients with sarcoidosis (47.8%), with nodularity (n = 23 [17.2%]), plaque (n = 19 [14.2%]), and increased vascularity (n = 19 [14.2%]) being the most prevalent. The diagnostic yield of EBB was 36.6%. AAs were significantly more prevalent in patients with than in those without nonnecrotizing granulomas on EBB (67.4% vs 36.5%; P = .001). Likewise, parenchymal disease on CT scan imaging was significantly more common in patients with than in those without nonnecrotizing granulomas on EBB (79.6% vs 54.1%; P = .003). On a per-lesion analysis, nonnecrotizing granulomas were seen especially in EBB samples obtained from areas of cobblestoning (9/10 [90%]) and nodularity (17/29 [58.6%]). The overall diagnostic yield of random EBB was low (31/134 [23.1%]). The interobserver agreement for the different patterns of AA was fair (Fleiss κ = 0.34). Interpretation In a population with a large prevalence of White Europeans, HD videobronchoscopy detected AAs in approximately one-half of patients with sarcoidosis. The diagnostic yield of EBB was higher in patients with parenchymal involvement on CT scan imaging and in those with AAs, especially if manifesting as cobblestoning and nodularity. Trial Registry ClinicalTrials.gov; No.: NCT4743596; URL: www.clinicaltrials.gov

][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21] However, some clinical predictors of EBB success generally are agreed on.[7] In some geographic settings such as Europe, the prevalence of sarcoidosis-associated endobronchial abnormalities was found to be low in studies performed with white light bronchoscopy or standard definition videobronchoscopy. 15,16An imaging method that helped to detect AAs when they are present but not plainly visible with conventional bronchoscopic imaging tools theoretically could help to increase the diagnostic yield of EBB.The recent introduction of high-definition (HD) videobronchoscopes, which provide high-resolution images and real-time optical or digital enhancement techniques, might help to detect subtle sarcoidosisassociated AAs and to characterize various patterns of airway involvement.The present study was aimed at evaluating the diagnostic yield of EBB guided by HD videobronchoscopy, the prevalence of different patterns of AAs, and the detection rate of granulomas associated with different patterns of AAs in patients with suspected sarcoidosis.

Study Design and Patients
This international multicenter prospective cohort study was approved by the ethics committee of each participating center (Rome, Amsterdam, Moscow, Bologna, and Saint Petersburg).Patients demonstrating clinical and radiologic suspicion of sarcoidosis were recruited consecutively between April 1, 2021, and March 31, 2022.Inclusion criteria were as follows: (1) indication for pathologic confirmation of a clinical and radiologic (CT scan imaging) suspicion of sarcoidosis, (2) age older than 18 years, (3) American Society of Anesthesiologists score of 1 to 3. Exclusion criteria were: (1) inability or unwillingness to consent to participate, (2) steroid therapy (at least 1 week) in the 2 months preceding bronchoscopy, (3) pregnancy, (4) uncontrolled coagulopathy, and (5) contraindication to the temporary interruption of anticoagulants or antiplatelet drugs, except aspirin.

Procedure
Bronchoscopies were performed in each center with the same equipment (Pentax EB15-J10 HD videobronchoscopes coupled with the Defina EPK 3000 processor), identical software settings

Take-home Points
Study Question: What is the role of high-definition (HD) videobronchoscopy in the identification of sarcoidosis-associated airway abnormalities (AAs)?Results: HD videobronchoscopy identified AAs in approximately one-half of patients with sarcoidosis.Patients with AAs and those with parenchymal disease on CT scan imaging were significantly more likely to have nonnecrotizing granulomas identified in endobronchial biopsy (EBB) samples.The diagnostic yield of EBB samples was highest in patients with cobblestoning and nodularity patterns and lowest in patients with increased vascularity.Interpretation: Given its simple technical performance, low morbidity, and nonnegligible diagnostic yield for the detection of granulomas, we suggest that EBB be used in patients with clinicoradiologic suspicion of sarcoidosis featuring any AA other than the increased vascularity pattern.(e-Appendix 1), and a standardized workflow, as described herein.Briefly, the airways of each patient enrolled first were inspected with the HD videobronchoscope.When AAs were identified, they were characterized further with the surface enhancement (surface enhancement,i-scan 1) and surface plus tone enhancement (tone enhancement mode c,i-scan 2) digital image enhancement technologies, which are integrated in the previously mentioned equipment.Every AA was recorded in a 10-to 15-s video and was classified by the bronchoscopist performing the procedure according to one of six patterns, predefined by the investigators in a meeting held before the study commenced as follows: EBBs were performed with standard 1.9-mm cupped flexible forceps according to a prespecified protocol: in patients with no endobronchial abnormalities, six biopsy samples were obtained randomly from normal-appearing airway mucosa, whereas in those with AAs, four biopsy samples were obtained from abnormal-appearing areas and two biopsy samples were obtained from normally appearing airway mucosa.Random biopsy samples were obtained from both the right and left airways, but the precise location was left to the discretion of the operators.In patients with different patterns of AAs or different areas of AA belonging to the same pattern, the decision to sample one or more such areas was left to the discretion of the operator.Biopsy samples from each area of abnormal-appearing airway mucosa as well as the biopsies from normal areas were collected in separate vials and were analyzed separately.All the biopsy samples were reviewed by a single pathologist, who was the assigned physician at the time of bronchoscopic sampling and was masked to the endoscopic findings.
Ancillary sampling procedures other than EBB (eg, endobronchial ultrasound-guided transbronchial needle aspiration [EBUS-TBNA], BAL, transbronchial lung biopsy, and transbronchial lung cryobiopsy) were allowed and were performed in the same session at the discretion of the operator, after the endobronchial inspection and biopsy.A sample for microbiologic testing (culture for bacteria and fungi, polymerase chain reaction, and culture for mycobacteria) always was obtained to rule out an infectious cause.
The final diagnosis of sarcoidosis was assigned after review of the clinical, radiologic, microbiologic, and pathologic information by the respiratory physicians running the outpatient sarcoidosis clinic at each enrolling center, after board discussion for low-confidence diagnostic cases.The interventional pulmonologists performing the study procedures were not involved in the final diagnosis assignment process. 22When the invasive sampling procedures failed to demonstrate a nonnecrotizing granulomatous inflammation in at least one organ, a clinicoradiologic re-evaluation at 6 months was required to confirm or exclude a provisional diagnosis of sarcoidosis.The follow-up was carried out in sarcoidosis clinics at each enrolled center and took into account the results of follow-up tests (including PET scans and biomarkers) performed in the 6 months after the initial bronchoscopy.

Study End Points
The primary outcome of the study was the diagnostic yield of the endobronchial biopsy for the detection of granulomas, on a perpatient basis.Secondary outcomes were: (1) overall prevalence of AAs identified with HD videobronchoscopy in patients with sarcoidosis; (2) prevalence of the different patterns of AAs in patients with sarcoidosis; (3) specificity for the detection of granulomas for each predefined pattern of AA; (4) diagnostic yield for the detection of endobronchial granulomas according to

Results
During the study period, 172 patients were evaluated for eligibility and 152 were enrolled (e-Fig 1).EBB was the only diagnostic bronchoscopic sampling method in 5 of 134 patients (3.7%).The other sampling methods yielding nonnecrotizing granulomas in our cohort were EBUS-TBNA in 103 patients, endoscopic ultrasound B with fine-needle aspiration in one patient, and transbronchial biopsy with standard forceps or with a cryoprobe in 14 patients.
Ninety-three mucosal areas were sampled in the 64 patients with AAs.In a per-lesion analysis, areas of cobblestoning (90%) and nodularity (58.6%) were  2).In a multivariate analysis, the increased vascularity pattern was found to be an independent predictor of negative EBB results (e-Table 1).
The interobserver agreement between the operator performing the procedure and three operators from centers not enrolling patients for patterns of AAs was fair (Fleiss' combined k ¼ 0.34).Among individual patterns, the agreement was substantial for areas of cobblestoning (Fleiss' k ¼ 0.62); was moderate for

Discussion
The present study evaluated HD videobronchoscopy for the detection of airway involvement in sarcoidosis and found tracheal or bronchial abnormalities, or both, in approximately one-half of patients (47.8%).This prevalence of AAs is much higher than that reported in the European studies on this matter.In a retrospective study conducted in Poland, Dziedzic et al 15 performed EBB in 340 patients with suspected sarcoidosis and found AAs only in 52 patients (15.6%).Goktalay et al 16 identified AAs in 20 of 59 patients (33.9%) with sarcoidosis, of whom seven had evidence of "extrinsic compression" rather than a mucosal abnormality.These figures provide preliminary evidence that HD videobronchoscopy might allow the identification of subtle airway changes that fiber-optic bronchoscopy or standard-definition videobronchoscopy are unable to detect.
In our study, the probability of detecting nonnecrotizing granulomas in EBB specimens was affected by the presence of AAs and of parenchymal involvement on CT scan imaging.Indeed, patients with AAs showed a significantly higher yield of EBB for the detection of nonnecrotizing granulomas than those with isolated lymphadenopathy.Although this finding is in line with the results of previous studies, [5][6][7][8][9][10]16 we tried for the first time to assess in a systematic fashion the prevalence and diagnostic yield associated with different patterns of AAs. Nodlarity, plaque, and increased vascularity were the patterns detected more frequently, whereas the diagnostic yield of EBB was highest in specimens retrieved from areas of nodularity and cobblestoning.On the contrary, biopsy samples from areas of increased vascularity were associated with  chestjournal.orga very low diagnostic yield.Unfortunately, the overall interobserver agreement for patterns of AAs was only fair (k ¼ 0.34) and was substantial only for areas of cobblestoning (k ¼ 0.62).This aspect highlights the subjectivity of the categorization of the endoscopic findings, which is common to both neoplastic and nonneoplastic conditions.23,24 The detection of granulomas in EBB specimens was significantly higher in patients with parenchymal involvement on chest CT scan imaging than those with isolated lymphadenopathy in this cohort.We believe that two main factors should be considered to explain this finding.First, patients with parenchymal involvement showed a slightly higher prevalence of AAs, a finding that has been associated with an increased yield of EBB in most previous studies.[5][6][7][8][9][10]16 Another possible explanation would contemplate a different (ie, higher) burden of granulomas in the airways of patients with parenchymal involvement as compared with those with isolated lymphadenopathy on imaging studies.Notably, a different density of granulomas in different radiographic stages of sarcoidosis has been suggested to explain the higher yield observed with transbronchial lung biopsy in stages II and III, 25,26 as well as with endosonography (EBUS-TBNA, endoscopic ultrasound B with fine-needle aspiration) in stage I. 27,28 In previous studies, the detection rate of granulomas in EBB according to the Scadding stage assessed by chest radiography was variable.Most found a higher yield in stages characterized by the presence of parenchymal involvement (stages II-III), 9,10,12,14,16,17 but others did not show any differences 21 or even found a higher yield in stage I disease.6,15 This can be explained partially by the subjectivity and poor accuracy of the sarcoidosis stage classification based on chest radiography findings.29 Interestingly, in a large randomized study aimed at comparing EBUS-TBNA vs conventional TBNA in sarcoidosis, Gupta et al 9 found that 33% of the patients classified as having stage I disease based on the chest radiography findings indeed showed parenchymal involvement on CT scan imaging.
14,17 However, in most previous studies, EBB was not performed in all patients with sarcoidosis diagnosed during the study period, leaving the presumption that EBB was performed mostly in patients with endobronchial changes, and leading to a selection bias.In a US study in which a 71% yield was obtained with EBB, only 56 of 150 patients who received a diagnosis of sarcoidosis during the study period underwent EBB; the authors explicitly state, "EBB were taken primarily from patients with abnormal bronchoscopic findings (52 of 56 patients)."5 Furthermore, the high yield of EBB (57%-71%) was achieved in US sarcoidosis populations, [5][6][7] which included a high proportion of African American patients and was never confirmed by studies conducted in Asia (6%-49%), [8][9][10][11]20,30 Europe (18%-45%), [14][15][16][17][18][19] or Oceania (27%-28%), 13,21 a result that suggests a key role played by ethnicity.
2][33] Therefore, it is unsurprising that the added value of EBB in our study, in which endosonography was used along with EBB in most patients, was only 3.7%.
Recently, pilot studies assessed the possible role of image-enhancing technologies in the detection of AAs in sarcoidosis.In a case report, Hakim et al 34 described the usefulness of narrow band imaging, an optical image-enhancing technology largely used for the detection of premalignant and early malignant mucosal lesions, in the identification and sampling of small hypovascular sarcoidosis-related nodular lesions.More recently, Dhooria et al 30 demonstrated a higher sensitivity of narrow band imaging when compared with conventional white light bronchoscopy to detect AAs in sarcoidosis in a small retrospective study.A large randomized trial (ClinicalTrials.govIdentifier: NCT05311150) aimed at comparing the diagnostic yield of EBB guided by narrow band imaging or white light bronchoscopy for the diagnosis of endobronchial sarcoidosis currently is ongoing.In the present study, we used the i-scan, a digital image enhancement technology that provides the physician with an enhanced view of the mucosal structures (i-scan 1) and the vascular patterns (i-scan 2), supporting early detection, characterization, and demarcation. 24,35We found the i-scan technology useful because it increased our confidence in the identification and characterization of subtle mucosal changes (Video 1), especially small hypovascular lesions (Video 2), as compared with the standard HD method.However, the extent to which this technology may increase the detection of subtle airway changes or characterize their pattern better needs to be assessed rigorously in future studies using the i-scan as a predefined end point.
The prospective international multicenter design, the large sample size, and the systematic assessment of AAs categorized as different patterns defined a priori are the strengths of our study.However, some limitations need to be acknowledged.First, the study population had specific demographic (large prevalence of White Europeans), clinical (approximately two-thirds of the patients with parenchymal involvement resulting from sarcoidosis), and endoscopic (47.8% with AAs) features.Therefore, the reproducibility of our results in populations with different characteristics is uncertain.Second, a formal sample size calculation was not performed because no previous study had explored the yield of EBB guided by HD videobronchoscopy for the diagnosis of tracheobronchial sarcoidosis, and the yield of EBB in studies that used white light bronchoscopy or standard definition videobronchoscopy was widely variable.Finally, because of the referral base of our bronchoscopy practices, the prevalence of extrathoracic involvement resulting from sarcoidosis was not captured in this study.However, we believe that although this is meaningful information, it does not affect the relevance of our study's results.
A. Gemelli IRCCS, the Department of Cardiovascular and Pulmonary Sciences (R. T.), Catholic University of the Sacred Hearth, Rome, the Interventional Pulmonology Unit (P. C. and M. F.), IRCCS Azienda Ospedaliero-Universitaria di Bologna, Bologna, the Clinical Epidemiology and Medical Statistics Unit (M.P. and G. S.), Department of Medicine, Surgery and Pharmacy, University of Sassari, Sassari, Italy; the Endoscopy Department (I.S.), the Department of Pathomorphology, Cell Biology and Biochemistry (L. A. S.), Central TB Research Institute, Moscow, Russia; the State Research Institute of Phtisiopulmonology (I.V.), St. Petersburg, Russia; the Department of Respiratory Medicine (J.T. A. and T. K.), Amsterdam UMC, Amsterdam, The Netherlands; the Department of Pulmonary, Critical Care and Sleep Medicine (K.M.), All India Institute of Medical Sciences, New Delhi, India; the Department of Thoracic Medicine (D. F.), The Royal Brisbane & Women's Hospital, the UQ Centre for Clinical Research (D. F.), Faculty of Medicine, The University of Queensland, Brisbane, QLD, Australia; and the Section of Pulmonary and Critical Care Medicine/Interventional Pulmonology (S.M.), The University of Chicago, Chicago, IL.Drs Sotgiu and Trisolini contributed equally to this manuscript.
(1) cobblestoning, ie, the presence of nodules coalescing in a larger infiltrative area (Fig 1A-B); (2) thickening, ie, the presence of smooth or irregular swelling of the mucosa involving a carina (Fig 1C-D); (3) nodularity, ie, the presence of small, discrete nodules (Fig 1E-F); (4) plaque, ie, the presence of infiltrative, raised, or flat whitish or yellow discrete area(s) not involving a carina (Fig 2A-B); (5) increased vascularity, ie, the presence of marked hyperemia or marked increase of submucosal vessel visibility, diffuse or regional (Fig 2C-D); and (6) miscellaneous, ie, the presence of an AA not well described by one of the previous patterns (Fig 2E-F).
Data are presented as No. (%) or median (interquartile range), unless otherwise indicated.Boldface indicates statistical significance.AA ¼ airway abnormality; EBB ¼ endobronchial biopsy.a Per-patient analysis.b Per-lesion analysis.

TABLE 1 ]
Baseline Demographic and Clinical Characteristics of the 152 Patients With and Without Sarcoidosis Enrolled in the Study Data are presented as No. (%) or median (interquartile range), unless otherwise indicated.AA ¼ airway abnormality.a Diagnosed in the 5 years preceding the patient's enrollment in the present study.b Total AA amounts to > 64 in the sarcoidosis cohort because in some patients more than one AA was identified and sampled.and AAs (P ¼ .001),especially areas of cobblestoning (P ¼ .02)and of nodularity (P ¼ .004),were observed more frequently in patients with positive EBB findings, whereas areas of increased vascularity were significantly more frequent (P < .0001) in patients with negative EBB findings (Table

TABLE 2 ]
Demographic, Clinical, and Endoscopic Characteristics by EBB Results